Patterned media poses unique challenges to the tribological properties of hard disks because typical fabrication processes can involve producing topography (e.g., grooves) in the magnetic media layers. The non-planar media surface can adversely affect a disk drive's performance in terms of both head flyability and corrosion. In conventional hard disk media, the head flies over a very smooth surface and the magnetic layers, which are composite metal films, are capped with a thin diamond-like carbon (DLC) film to protect against corrosion. In patterned media, a DLC film is also typically required to cap the magnetic layers, but the presence of topography in the magnetic layers can result in poor conformal coverage (e.g., groove sidewalls and corners) resulting in inadequate corrosion performance.
In conventional fabrication process for patterned media, the DLC film is applied to the pattern features of the discrete track recording (DTR) disk, also referred to as discrete track media (DTM). One type of DTM structure utilizes a pattern of concentric discrete zones for the recording medium. When data are written to the recoding medium, the discrete magnetic areas correspond to the data tracks. The substrate surface areas not containing the magnetic material isolate the data tracks from one another. The discrete magnetic zones (also known as hills, lands, elevations, etc.) are used for storing data and the non-magnetic zones (also known as troughs, valleys, grooves, etc.) provide inter-track isolation to reduce noise. The lands have a width less than the width of the recording head such that portions of the head extend over the troughs during operation. The lands are sufficiently close to the head to enable the writing of data in the magnetic layer. Therefore, with DTM, data tracks are defined both physically and magnetically
In conventional fabrication of DTM, the recessed (e.g., grooves) and non-recessed regions (e.g., lands) of the patterned area are coated at the same time using the same diamond-like carbon (DLC) deposition process. As a result, the coating of the recessed regions will be thinner and less uniform than the non-recessed regions because of shadowing effects and a larger surface area in the recessed regions. Consequently, the potential for corrosion in the recessed regions of the patterned media is greater than the non-recessed regions and likewise greater than standard non-patterned media.
One conventional DTM fabrication approach uses a physical vapor deposition (PVD) technique to coated the entire surface of patterned magnetic layer. Such an approach may involve multi-steps of depositing and etching back films to completely fill recessed regions of the patterned media and achieve a flyable surface.
Another conventional DTM fabrication method described in US 2008/0187779 utilizes atomic layer deposition (ALD) to deposit a DLC film over the entire surface of the patterned magnetic recording layer, after installing a resin mold mask on the surface of magnetic recording layer. The ALD fills not only the grooves but also covers the resin mold mask on the lands of the magnetic recording layer. Then, the resin mold mask is removed together with the ALD protective layer above the lands of the magnetic recording layer.